The present invention relates in general to elevator doors, and, more specifically, to an adjustable control cable for a door restrictor.
Automatic door systems on elevators must meet a requirement that elevator passengers be unable to open the car door from inside when the elevator car is beyond the door opening zone of a floor. Since regulations associated with this requirement are not very old, there remain very many elevator installations currently without a mechanism to prevent such opening. The door systems of such elevator installations must now be adapted to the present regulations, presenting the problem of updating nonconforming door systems with the smallest possible intrusion into the existing construction while minimizing additional parts and cost.
One solution is shown in U.S. Pat. No. 5,377,785 which is incorporated herein by reference. This patent shows a door locking system for retrofit installation on an automatic sliding door of an elevator car. At floor stops, the car door is coupled via cams and couplings with the hoistway door and is opened and closed together therewith. The locking system prohibits opening of the elevator door from the inside of the car when the car is between two floors (i.e., outside the door opening zone of a floor) by means of a rocker mechanism affixed to a fixed or movable cam of a clutch and coupling mechanism of the door. The rocker mechanism is tilted by coupler brackets of the hoistway door during normal operation of the door within the door opening zone. A cable wire connected between the rocker mechanism and a locking pawl disengages the locking pawl from a hook retainer to mechanically free the door for opening. The rocker mechanism is not actuatable outside of the door opening zone. The locking pawl is kept in a mechanically interlocked position by a compression spring when the rocker mechanism is not actuated, thereby preventing the door from opening.
The cable wire passes through a sheath or housing which creates a certain path length between the rocker mechanism and the locking pawl. For reliability of the locking system, cable stresses need to be kept low. Due to the arrangement of the cable wire, sheath, and locking pawl, actuation of the locking pawl causes the cable wire to bend. A single door locking system often goes through as many as one million locking/unlocking cycles in one year. The repeated sharp bending of the cable wire at a pinch point can lead to premature failure of the cable wire. Cable failure could mean that a door could stay locked even with the elevator car in the door opening zone. Therefore, kinking or potential pinching of the cable wire anywhere between the securing points at its ends should be avoided. Besides setting a path length and constraining the cable wire, the housing protects the cable wire from damage or kinking.
A retainer retains one end of the cable wire at the rocker mechanism. The locking pawl includes an adjusting bolt extending from one end of the pawl arm which retains an eye ring at the other end of the cable wire. Accurate actuation of the pawl mechanism depends on accurate control of the path length determined by the length of the sheath and the actual length of cable wire between the rocker mechanism and the locking pawl. The adjusting bolt on the locking pawl can be retracted or extended to change the effective length of the pawl arm and consequently the leverage of the locking pawl. However, the adjustment has little effect on the effective length of the cable wire. Therefore, variations in individual dimensions or changes (e.g., stretching) over time cannot be well compensated.
The present invention has the advantage of making fine adjustments in the disengagement of the locking pawl with a small number of inexpensive parts and reducing stress to the cable.
One aspect of the invention provides a door locking system for retrofit installation on an automatic sliding two-panel door of an elevator car which, at floor stops, is coupled with a hoistway door and is opened and closed together therewith. The locking system prohibits opening and closing of the door from the interior of the car when between two floors, that is, beyond a door opening zone of a floor. A locking pawl is mounted to a panel of the door. A hook retainer is mounted to be adjacent to the locking pawl when the door is closed so that the locking pawl is selectably engaged with the hook retainer. A drive mechanism has an unactivated position when the elevator car is between two floors and is movable to an activated position in response to the elevator car being located in the door opening zone. A cable coupled to the drive mechanism and to the locking pawl for disengaging the locking pawl from the hook retainer when the drive mechanism moves from the unactivated position to the activated position. A flexible cable housing slidably retains the cable and defines a path length between the drive mechanism and the locking pawl. A path length adjuster mechanism is connected between two sections of the cable housing for manually adjusting the path length. A hold-down is mounted to the door to retain the cable housing in close proximity to the door while permitting movement parallel with the door in response to adjustment of the path length.